Apparently this happened last night too, at about the same time, when the forum and most likely the main site have the fewest users (and no admins around), but last night almost nobody noticed. Maybe it was a quick test run. I think they are generating the bitcoin addresses on the fly and inserting them into the images so fast that they aren't even announced to the network and searchable on the block chain when you first see the images. Perhaps if we keep checking, more of them will show up. Announcing the addresses isn't critical. As long as you have the private key, you can claim the coins at a later date. It's just conventional to announce even unused addresses because people want to check and see that an address exists before they send coins to it.